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 * Copyright (c) 2009 Intel Corporation
 * All rights reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 *
 * -- Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * -- Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * -- Neither the name of the Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE INTEL OR ITS
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;

namespace VerseSharp
{
    public delegate void Connect0CommandCallback(byte[] exponent, byte[] modulus);
    public delegate void Connect1CommandCallback(byte version, uint timeSeconds, uint timeFractions, byte[] exponent, byte[] modulus);
    public delegate void Connect2CommandCallback(byte[] encryptedData);

    public class ConnectCommand : IVerseCommand
    {
        public CommandID ID { get { return CommandID.Connect; } }
        public byte Stage;

        public byte[] Exponent;
        public byte[] Modulus;
        public byte[] EncryptedData;

        public byte Version;
        public uint TimeSeconds;
        public uint TimeFractions;

        public void Deserialize(byte[] source, ref int pos)
        {
            Stage = source[pos++];

            switch (Stage)
            {
                case 0:
                    Exponent = new byte[VerseConstants.ENCRYPTION_KEY_SIZE];
                    Buffer.BlockCopy(source, pos, Exponent, 0, VerseConstants.ENCRYPTION_KEY_SIZE);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    Modulus = new byte[VerseConstants.ENCRYPTION_KEY_SIZE];
                    Buffer.BlockCopy(source, pos, Modulus, 0, VerseConstants.ENCRYPTION_KEY_SIZE);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    break;
                case 1:
                    Version = source[pos++];
                    TimeSeconds = DataConverter.BigEndian.GetUInt32(source, pos);
                    pos += 4;
                    TimeFractions = DataConverter.BigEndian.GetUInt32(source, pos);
                    pos += 4;
                    Exponent = new byte[VerseConstants.ENCRYPTION_KEY_SIZE];
                    Buffer.BlockCopy(source, pos, Exponent, 0, VerseConstants.ENCRYPTION_KEY_SIZE);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    Modulus = new byte[VerseConstants.ENCRYPTION_KEY_SIZE];
                    Buffer.BlockCopy(source, pos, Modulus, 0, VerseConstants.ENCRYPTION_KEY_SIZE);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    break;
                case 2:
                    EncryptedData = new byte[VerseConstants.ENCRYPTION_KEY_SIZE];
                    Buffer.BlockCopy(source, pos, EncryptedData, 0, VerseConstants.ENCRYPTION_KEY_SIZE);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    break;
                default:
                    LogAdapter.Warn("Unrecognized connect packet");
                    break;
            }
        }

        public void Serialize(byte[] destination, ref int pos)
        {
            destination[pos++] = Stage;

            switch (Stage)
            {
                case 0:
                    Check.Require(Exponent, "Exponent");
                    Check.Require(Modulus, "Modulus");

                    Buffer.BlockCopy(Exponent, 0, destination, pos + (VerseConstants.ENCRYPTION_KEY_SIZE - Exponent.Length), Exponent.Length);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    Buffer.BlockCopy(Modulus, 0, destination, pos, VerseConstants.ENCRYPTION_KEY_SIZE);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    break;
                case 1:
                    Check.NotEqual(Version, 0, "Version");
                    Check.Require(Exponent, "Exponent");
                    Check.Require(Modulus, "Modulus");

                    destination[pos++] = Version;
                    DataConverter.BigEndian.PutBytes(destination, pos, TimeSeconds);
                    pos += 4;
                    DataConverter.BigEndian.PutBytes(destination, pos, TimeFractions);
                    pos += 4;
                    Buffer.BlockCopy(Exponent, 0, destination, pos + (VerseConstants.ENCRYPTION_KEY_SIZE - Exponent.Length), Exponent.Length);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    Buffer.BlockCopy(Modulus, 0, destination, pos, VerseConstants.ENCRYPTION_KEY_SIZE);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    break;
                case 2:
                    Check.Require(EncryptedData, "EncryptedData");

                    Buffer.BlockCopy(EncryptedData, 0, destination, pos, VerseConstants.ENCRYPTION_KEY_SIZE);
                    pos += VerseConstants.ENCRYPTION_KEY_SIZE;
                    break;
                default:
                    throw new InvalidOperationException("Unknown Stage: " + Stage.ToString());
            }
        }
    }
}
